1. Field of the Invention
The present invention relates to an adhesive sheet for affixation of a wafer and a method for processing using the same. More particularly, the present invention relates to an adhesive sheet for affixation of a wafer used in dicing of a semiconductor wafer into chips and to a method for dicing a semiconductor wafer by using the same.
2. Description of the Related Art
In general, semiconductor wafers made of silicon, gallium arsenide, etc., are manufactured in the condition of having a large diameter. This wafer is cut and separated (diced) into element chips and, thereafter, the resulting chips are subjected to a mounting step. Conventionally, the semiconductor wafer is subjected to each step of dicing, cleaning, drying, expanding, picking up and mounting in the condition of being affixed to an adhesive sheet in advance. As the adhesive sheet for affixation of a wafer used in dicing, sheets described in, for example, Japanese Patent Laid-Open No. 7-86212, are known. The adhesive sheet for affixation of a wafer described in Japanese Patent Laid-Open No. 7-86212 is composed of a radiation-setting adhesive layer arranged on a substrate. This sheet can be peeled away from a semiconductor wafer with ease by being irradiated with radioactive rays after dicing.
However, there is the following problem in the method for processing using the aforementioned conventional adhesive sheet for affixation of a wafer. That is, when there is another step between the steps of picking up and mounting, foreign matter, etc., may adhere to even a chip having been already cleaned and dried. In particular, since the back of the chip becomes a mounting surface, when adhesion of foreign matter, etc., occurs, problems of reduction in mounting precision, etc., are brought about.